Research And Design Of Concurrent Muiti-band Low Noise Amplifier

As an important module of modern wireless communication systems, microwaveamplifiers play a significant role in the whole performance of the systems. With thedevelopment of the Third Generation mobile communications, the requirements of thesystems supporting multi-mode and multi-standard operation become necessary inrecent years, which promotes the study of multi-band low noise microwave amplifiers(LNA). On the basis of research on the fundamental theory and analysis method of lownoise microwave amplifiers, the multi-band techniques are mainly focused on, and aconcurrent multi-band low noise amplifier is also presented.Firstly, after reviewing and summarizing the history and present situation of thelow noise amplifier, the specifications, and its design theory, principle, method areexpounded. Then, on the basis of the literature, several popular implementationschemes at present of multi-band techniques in microwave amplifiers are introducedand their relative merits are also summarized. Finally, this paper designs a concurrenttriple-band LNA suitable for both WLAN and WiMAX applications covering2.4-2.7GHz,3.3-3.8GHz and5.1-5.9GHz. The proposed LNA consists of two cascadedcommon-source stages and employs stepped-impedance transformers and series andshunt feedback techniques to obtain good return loss, low noise and high linearitysimultaneously. Test results show that the LNA features input and output return loss of12dB, gain of21dB, and noise figure of2dB across the three bands of operation,which are the state of the art among the counterparts.